THE SPATIAL VARIABILITY OF LARGE SCALE SAND BARS

Abstract

In this work we describe preliminary results from a newly developed aerial video system which can be used to rapidly (2-4 hours) and accurately (5 m resolution) sample the horizontal scales of sand bar morphology over several hundred km's of coastline. Observations from, for example, the North Carolina coastline on the central eastern seaboard of the U. S., indicate marked changes in the alongshore morphological patterns, which can be cyclic with lengths scales of 5-10 km's along one stretch of coast but adjacently the bars can be absent altogether. Other observations from the lower sloping west coast beaches of the U. S. Pacific Northwest show highly complex sand bar morphology which also exhibit marked alongshore variability. Along this coast the beach systems are not continuous and are separated by large headlands, and the morphology at any particular beach behaves independently from the bar morphology in adjacent compartments.